Field of the Invention
The present invention relates to a method and apparatus for measuring the flowability of powdered or granular materials.
The measurement of the fluid characteristics of powdered or granular materials is a critical factor in planning and designing dispensing devices for such materials in the food processing industry and in the processing of pharmaceuticals. Indeed, in many manufacturing processes it is necessary to convey predetermined amounts of granular or powder material from a supply hopper to a blending or packaging apparatus. With such manufacturing processes, it is critical that a predetermined amount of the material be accurately dispensed and that sequential batches have identical compositions. In order for an accurate and reproducible amount of material to be conveyed from the hopper, the precise flowability of the material within the hopper must be uniform and controlable.
An example of a prior art flow meter is the Photron Flowable Solids Quantifier available from Grover Scientific, Inc. of Saratoga, Calif. The Photron device includes a screen through which the material to be tested passes and elements for agitating the material so it will flow to and through the screen. The agitating elements are spring biased and are actuated by a trigger assembly which is operated by a technician. Because the Photron has a number of moving parts and must be continuously actuated by a technician, and because flow through the screen cannot be selectively prevented, accurate and reproducible results are difficult to obtain.
While a variety of methods for testing the flowability of materials have been developed, presently there is no known satisfactory method for measuring the relative flowability of powdered materials in a manner which is both reproducible and accurate. As noted above, however, there is a need for such a reliable method of determining the flowability of materials having different physical characteristics as well as the flow of a particular material under varying physical conditions. Indeed, the particle shape, size and size distribution of the material will influence the flow rate of a particular material. Furthermore, varying physical conditions such as temperature, moisture content and the like will influence the flow rate of a particular material.
It would therefore be desirable to provide a simple, accurate and reproducible measuring device which enables the quick and easy determination of the flowability of materials such as seasonings and pharmaceuticals.